1. Field of the Invention
The present invention generally relates to a polymer which can be used as a photolithography processing material and a resist composition comprising the same. More particularly, the present invention relates to a novel polymer having a high level of transmittance at deep ultraviolet (DUV) from a next-generation ArF excimer laser (193 nm), and a chemically amplified resist composition comprising the same.
2. Description of the Related Art
As the integration density and complexity of semiconductor devices continue to increase, the ability to form ultra-fine patterns becomes more and more critical. For example, in 1-Gigabit or higher semiconductor devices, a pattern size having a design rule of 0.1 xcexcm or less is needed. When a conventional photoresist material is exposed with a KrF excimer laser (248 nm), however, it is difficult to form such fine patterns. For this reason, a lithography technique using an ArF excimer laser (193 nm) generating at a wavelength that is shorter than the wavelength of a KrF excimer laser, has been actively researched. With this research into ArF excimer lasers, new resist materials that would be compatible with ArF excimer lasers are needed and required.
Polymer materials used in photolithography are required to meet the following requirements: (1) high transparency for the corresponding light source; (2) high resistance against a plasma used during a dry etching process; (3) good adhesion to underlying layers to avoid pattern collapse; and (4) capability of being developed using a conventional developer.
To date, several resist materials for use in lithography using ArF excimer laser have been found, and representative examples thereof include polymers prepared from poly(meth)acrylate, cycloolefin-maleic anhydride (COMA), polynorbornene and the like. However, these polymers have several limitations in satisfying the above requirements. Particularly, these polymer materials may have very low transparency, a very weak resistance against a dry etching process, and poor adhesion to underlying layers. Thus, these conventional resist materials still have several drawbacks and present problems in commercial use with ArF excimer lasers.
According to an embodiment of the present invention, there is provided a polymer having a structure which can be prepared by a simple method and has a high transmittance, improved dry etching resistance and good adhesiveness when used as a resist composition material.
Another feature of an embodiment of the present invention provides a resist composition which provides a high transmittance in lithography, good dry etching resistance, and good adhesiveness to underlying layers, that may be advantageously used for realizing very small pattern sizes as well as easily employed for commercial use with ArF excimer lasers without the drawbacks and problems of conventional resist materials.
According to another feature of an embodiment of the present invention, there is provided a polymer having a repeating unit comprising a copolymer of butadiene sulfone and maleic anhydride, the copolymer represented by a Formula 1:
[Formula 1]
In another embodiment of the present invention, the polymer includes (a) a first repeating unit comprising a copolymer of butadiene sulfone and maleic anhydride, the copolymer being represented by a Formula 1, and (b) a second repeating unit copolymerized with the first repeating unit.
The polymer according to the present invention has a weight average molecular weight of 3,000 to 30,000.
The second repeating unit includes a hydroxy, carboxyl, or acid-labile group. The second repeating unit is a polymerization product obtained from at least one monomer selected from-the group consisting of acrylate, methacrylate, norbornene, alkyl vinyl ether, vinyl acetate, acrolein, methacrolein, acrylonitrile and methacrylonitrile.
Alternatively, the polymer according to another embodiment of the present invention may have a Formula 2:
[Formula 2]
wherein R1 is a hydrogen atom or a methyl group, R2 is a substituted or unsubstituted C1-C20 hydrocarbon group, m/(m+p)=0.5 to 0.8, and p/(m+p)=0.2 to 0.5. Preferably, R2 is t-butyl, tetrahydropyranyl or 1-ethoxyethyl. Also, R2 is preferably a C4-C20 acid-labile alicyclic group, exemplified by 2-methyl-2-norbornyl, 2-ethyl-2-norbonyl, 2-methyl-2-isobornyl, 2-ethyl-2-isobornyl, 8-methyl-8-tricyclo[5.2.1.02,6]decanyl, 8-ethyl-8-tricyclo[5.2.1.02,6]decanyl, 2-methyl-2-adamantyl, 2-ethyl-2-adamantyl, 1-adamantyl-1-methylethyl, 2-methyl-2-fenchyl or 2-ethyl-2-fenchyl.
According to another embodiment of the present invention, the polymer may have a formula 3:
[Formula 3]
wherein R3 is a hydrogen atom, a hydroxy, carboxyl, halide, nitrile, alkyl, alkoxy, sulfonate, or a substituted or unsubstituted C1-C20 acid-labile hydrocarbon group, m/(m+q)=0.5 to 0.8, and q/(m+q)=0.2 to 0.5. Preferably, R3 is t-butyl ester, tetrahydropyranyl ester or 1-ethoxyethyl ester. Also, R3 is a preferably C4-C20 acid-labile alicyclic ester group, exemplified by 2-methyl-2-norbornyl ester, 2-ethyl-2-norbonyl ester, 2-methyl-2-isobornyl ester, 2-ethyl-2-isobornyl ester, 8-methyl-8-tricyclo[5.2.1.02,6]decanyl ester, 8-ethyl-8-tricyclo[5.2.1.02,6]decanyl ester, 2-methyl-2-adamantyl ester, 2-ethyl-2-adamantyl ester, 1-adamantyl-1-methylethyl ester, 2-methyl-2-fenchyl ester or 2-ethyl-2-fenchyl ester.
According to still another embodiment of the present invention, the polymer may have a Formula 4:
[Formula 4]
wherein, R1 is a hydrogen atom or a methyl group, R2 is a substituted or unsubstituted C1-C20 hydrocarbon group, R3 is a hydrogen atom, a hydroxy, carboxyl, halide, nitrile, alkyl, alkoxy, sulfonate, or a substituted or unsubstituted C1-C20 acid-labile hydrocarbon group, m/(m+p+q)=0.3 to 0.8, p/(m+p+q)=0.1 to 0.4 and, q/(m+p+q)=0.1 to 0.3. At least one of R2 and R3 includes an acid-labile group.
According to another feature of an embodiment of the present invention, there is provided a resist composition comprising (a) a photosensitive polymer including a repeating unit comprising a copolymer of butadiene sulfone and maleic anhydride, the copolymer represented by the formula 1, and (b) a photoacid generator (PAG).
The amount of the PAG is preferably from about 1 to about 15 wt % based on the weight of the photosensitive polymer. Preferably, the PAG includes triarylsulfonium salts, diaryliodonium salts, or mixtures thereof. More preferably, the PAG includes triphenylsulfonium triflate, diphenyliodonium triflate, di-t-butyldiphenyliodonium triflate, or mixtures thereof.
The resist composition according to an embodiment of the present invention may further include an organic base. The amount of the organic base is preferably from about 0.01 to about 2.0 wt % based on the weight of the photosensitive polymer. Preferably, the organic base includes a tertiary amine compound. More preferably, the organic base comprises triethylamine, triisobutylamine, triisooctylamine, diethanolamine, triethanolamine, or a mixture thereof.
The resist composition according to another embodiment of the present invention comprises: (a) a photosensitive polymer comprising: (a-1) a first repeating unit comprising a copolymer of butadiene sulfone and maleic anhydride, the copolymer represented by the formula 1, and (a-2) a second repeating unit copolymerized with the first repeating unit, and (b) a photoacid generator (PAG).
The second repeating unit includes a hydroxy, carboxyl, or acid-labile group. The second repeating unit is a polymerization product obtained from at least one monomer selected from the group consisting of acrylate, methacrylate, norbornene, alkyl vinyl ether, vinyl acetate, acrolein, methacrolein, acrylonitrile and methacrylonitrile.
The polymer according to the present invention has a repeating unit comprising a copolymer of strongly hydrophobic butadiene sulfone and maleic anhydride, thereby exhibiting good adhesiveness when used as a resist composition material.
The polymer of the present invention provides a high transparency at a deep ultraviolet (DUV) region and has good wettability to generally used developer solutions. Therefore, the resist composition prepared therefrom can be developed using conventional developer solutions. Also, the resist composition has excellent dry etching resistance, a high transmittance and good adhesion to the underlying layer, thereby exhibiting desirable lithographic performance.